Muffler with two longitudinally separated chambers



Oct. 5, 1965 w. c. WHITNEY v 3,209,861

MUFFLER WITH TWO mucmunmnw, sannnsn cmuasns Filed Oct. 28, 1963 INVENTOR.

United States Patent 3,209,861 MUFFLER WITH TWO LONGITUDINALLY SEPARATED CHAMBERS William (1. Whitney, Jackson, Mich, assiguor to Walker Manufacturing Company, a corporation of Delaware Filed Oct. 28, 1963, Ser. No. 319,456 2 Claims. (Cl. 181-59) My invention relates to automotive exhaust mufflers.

It is an object of my invention to provide an improved sport or Hollywood-type exhaust mufller. The invention accomplishes this by means of a simple, two-part construction comprising an outer shell and an inner gas flow tube. The shell is pinched down at an intermediate point to contact the tube and divide the space between theshell and the tube in the two longitudinally separated chambers. One of these may be filled with glass fibers or suitable sound absorbent material.

The invention is illustrated in the accompanying drawings in which:

FIGURE 1 is a longitudinal cross section through the muffler of this invention; and

FIG. 2 is a cross section along the line 2-2 of FIG. 1.

The mufller 1 has an outer shell 3 which is preferably formed from a tubular piece of metal which is swaged down to form an inlet end 5 and an outlet end 7 which are provided respectively with an inlet bushing 9 and an outlet bushing 11 for attachment to an exhaust pipe and a tailpipe in an automotive exhaust system. Inside of the shell 3 is a louvered gas flow tube 13 which is seated at opposite ends in the bushings 9 and 11 of the shell 3 and preferably spotwelded at x to one of them. The tube 13 may be provided with a restriction 15 which can be formed by rolling a reduced diameter section in the tube. The tube 13 is also provided with banks of louvers 17 which open into the space between the tube 13 and the shell 3.

The shell 3 is pinched down into contact with the tube 13 by pinching together folds of metal 19 so as to reduce the intermediate portions 21 into wrap around contact with the outside diameter of the tube 13. This divides the inside of the casing 3 into a chamber 23 upstream of the folds 19 and the chamber 25 downstream of the folds 19. One of the chambers, preferably the downstream chamber 23, is filled with sound absorbent material such as glass pack.

In operation, gas will enter the inet bushing 9 and flow lengthwise through the tube 13 to flow out of the unit through the outlet bushing 11. The restriction 15 imposes a controlled amount of back pressure on the gas and therefore facilitates an improves the silencing effect of the muffler 1. The gases passing through the tube 13 communicate with the space 23 where many of the intermediate and high frequency sounds are attenuated. A

substantial amount of additional attenuation occurs in the glass pack section 25. The intermediate and high frequencies are removed also by the glass pack 25 so that the unit as a whole has a substantially high eificiency in removing intermediate and high frequencies without utilizing a very large amount of glass pack material. The presence of the restriction 15 upstream of the glass pack tends to protect the glass pack againt loss by erosion, as

well as improve the silencing characteristics of the unit. The low frequencies are not effectively removed by this device so that it constitutes the Hollywood or sport-type mufiler which leaves the low power note in the exhaust system.

Modifications may be made without departing from the spirit and scope of the invention.

I claim:

1. A Hollywood type exhaust muffler for internal combustion engines comprising an outer shell of substantially uniform cross-sectional area throughout the major portion of its length with an intermediate section of reduced cross-section, an inner tube extending through said outer shell and engaged substantially around its periphery by said intermediate section to divide the space between said inner tube and said outer shell into two longitudinally separated chambers, said inner tube providing a straight through flow path throughout the length of said outer shell of substantially constant cross-sectional area through the major portion of its length, said inner tube having a plurality of openings into each of said chambers, one of said chambers being empty, and a sound absorbent substance filling the other of said chambers.

2. A Hollywood type exhaust mufiier as set forth in claim 1 wherein the inner tube is formed With an integral flow restriction of reduced cross-sectional area in one of said chambers.

References Cited by the Examiner UNITED STATES PATENTS 2,047,442 7/36 Starkweather et al 181-48 2,047,443 7/ 36 Starkweather, et al 181-35 2,056,608 10/36 Jack 181-42 X 2,194,457 3/40 Cary 181-35 2,251,880 8/41 Cary et al 181-48 2,367,753 1/45 Buck.

FOREIGN PATENTS 881,494 1/43 France.

988,370 4/51 France. 1,158,817 3/58 France. 1,063,136 12/53 France. 1,074,071 3/54 France.

892,780 3/ 62 Great Britain.

LEO SMILOW, Primary Examiner. 

1. A HOLLYWOOD TYPE EXHAUST MUFFLER FOR INTERNAL COMBUSTION ENGINES COMPRISING AN OUTER SHELL OF SUBSTANTIALLY UNIFORM CROSS-SECTIONAL AREA THROUGHOUT THE MAJOR PORTION OF ITS LENGTH WITH AN INTERMEDIATE SECTION OF REDUCED CROSS-SECTION, AN INNER TUBE EXTENDING THROUGH SAID OUTER SHELL AND ENGAGED SUBSTANTIALLY AROUND ITS PERIPHERY BY SAID INTERMEDIATE SECTION TO DIVIDE THE SPACE BETWEEN SAID INNER TUBE AND SAID OUTER SHELL INTO TWO LONGITUDINALLY SEPARATED CHAMBERS, SAID INNER TUBE PROVIDING A STRAIGHT THROUGH FLOW PATH THROUGHOUT THE LENGTH OF SAID OUTER SHELL OF SUBSTANTIALLY CONSTANT CROSS-SECTIONAL AREA THROUGH THE MAJOR PORTION OF ITS LENGTH, SAID INNER TUBE HAVING A PLURALITY OF OPENINGS INTO EACH OF SAID CHAMBERS, ONE OF SAID CHAMBERS BEING EMPTY, AND A SOUND ABSORBENT SUBSTANCE FILLING THE OTHER OF SAID CHAMBERS. 